Control devices which allow one person to control the use of an appliance by another person are known in the art. In its simpliest form, such control devices comprise a coin box interconnected with the circuitry of the appliance which actuates the appliance upon payment of a predetermined sum of money. One such system is described in U.S. Pat. No. 4,566,033 to Reidenoar. Fee charging apparatuses for television sets are also known and are commonly used in hotels. Examples of such fee charging systems are disclosed in U.S. Pat. Nos. 4,085,422 to Ninata et al; 4,012,583 to Kramer; and 4,700,296 to Palmer.
Control devices that allow a parent to selectively control the amount of time that a child uses an appliance such as a television set, are also known in the art. One such device is disclosed in U.S. Pat. No. 4,348,696. The control device disclosed in the patent to Beier records the viewing time of one or more viewers watching a controlled television set and turns the set off when a predetermined viewing time limit of any one of the viewers is exceeded. An individual password for each viewer is stored in the control device's internal memory along with a predetermined viewing time associated with each of the passwords. During the programmed viewing period (daily or weekly), the amount of viewing time remaining for each password code begins decreasing when the viewer turns on the control device. When the time remaining reaches zero, the television set is deactivated. However, when the assigned viewing period terminates the microprocessor automatically restores the predetermined viewing time to each of the password codes. Thus, for example, if a viewers time period is on a daily basis and is 120 minutes long, the viewers time limit will be restored to 120 minutes at the end of each day no matter how much of the previously allotted time was used.
One drawback to the control device disclosed in the patent to Beier is that once a predetermined amount of time is allotted to a viewer, that time cannot be altered until the end of the assigned viewing period. At that time, the control device will automatically restore each of the predetermined time limits for each password code. There is no mechanism by which the parent can manually increment or decrement the time alloted to a particular viewer prior to the end of the predetermined viewing period. Thus, a valuable opportunity to positively reinforce desired behavior or to discourage undesired behavior is lost.
The patent to Jackson, U.S. Pat. No. 4,081,754, also discloses a device for limiting the viewing periods throughout a predetermined time period i.e. one week. The device can be used to allow viewing on selected channels to the exclusion of all others during the predetermined periods.